Troopers said the crash, which killed Micah Phoenix, 37, and Yomadith Rodriguez Matos, 32, occurred shortly after 11 p.m. on 301 near Southwest 89th Street in Bradford County.
Phoenix's mother, Christina Johnson, told News4Jax that the family was watching TV when the couple decided to go for a walk.
Johnson said an officer knocked on her door at 3 a.m. with the news that her son and his girlfriend had been killed.
Rodriguez Matos and Phoenix died at the scene of the crash, which was just 2 miles from his home.
Family said the two had been dating for about a month, and Rodriguez Matos' brother told News4Jax she leaves behind three daughters, ages 12, 10 and 8.